The present invention relates to an occupant protective apparatus for use in a vehicle and, in particular, to an occupant id protective apparatus which is capable of reducing deceleration applied to an occupant when the vehicle collides.
Recently, in order to enhance the effect of occupant cu protection in a vehicle collision, there have been proposed various vehicle body structures in which the deforming mode of go the other remaining portions of a vehicle body than the passenger room of the vehicle body in a vehicle collision is set properly to thereby be able not only to reduce the deceleration of the passenger room of the vehicle body but also to prevent the deformation of the remaining portions of the vehicle body from extending over the passenger room of the vehicle body (see Japanese Patent Unexamined Publication No. Hei.7-101354).
On the other hand, the deceleration of the occupant constrained to a seat by a seat belt can firstly start at the time when a forwardly going inertial force acting on the occupant in the vehicle collision is received by the seat belt. Here, since the spring action of the seat belt cannot be removed completely, the inertial force causes the occupant to move forward and the deceleration of the occupant reaches its peak value at the time when the extension of the seat belt reaches its limit. It is generally said that the peak of the occupant deceleration increases as the moving amount of the occupant due to the inertial force increases and, normally, the peak of the occupant deceleration becomes higher than the average deceleration of the passenger room of the vehicle body. Therefore, in order to reduce an impact to be given against the occupant due to the vehicle collision, the deceleration of the vehicle body must be adjusted in such a manner that a delay in the starting time of the occupant deceleration with respect to the vehicle body deceleration can be minimized.
However, it is substantially impossible to connect the occupant to the vehicle body as an integral unit and, especially, in the case of a compact vehicle in which it is difficult to secure a sufficient stroke in the other remaining portions of the vehicle body than the passenger room thereof, it is difficult to reduce the occupant deceleration further simply using a conventional occupant protecting method in which the deceleration of the passenger room in a vehicle collision is reduced by properly setting the deforming stress of the vehicle body.